The answer depends on who you talk to.
Personally, I'm not sure if there is a conclusive reply to your question because there are a lot of contradictions, even among experts. Some hobbyists swear by it; for example, some suggest it is essential for Xenia corals, while others claim in some cases Xenia is harmed by it. Some claim that it can build to dangerous levels, others have written that it is so rapidly depleted by a protein skimmer and ozonizer, that it must be supplemented constantly.

Some advocates of iodine suggest it prevents damage from intense light that ultimately leads to bleaching in reef inverts like clams and corals, but has that been scientifically proven? I don't know. Some reefers add it along with other supplements, some prefer a time released iodine, others turn off the skimmer after adding it, to provide their animals a better chance to "absorb" it. (?) Aquarists may be led to conclusions based on anecdotal evidence; but that is not always scientific (too many variables).

Here's the problem; if it's difficult to reliably test for, then it's hard to know where you are, and even harder to make statements with any authority. Unfortunately, there doesn't seem to be any serious scientific data showing a specific method leading to a direct benefit; some tests have been done on macroalgae, but the results were not very positive. See below from R. Holmes-Farley:

"I would strongly advise people to not try to maintain 0.06 ppm iodine using supplementation and a test kit... if we could easily and accurately determine the concentrations of the different forms of iodine in aquaria, then I would recommend doing just that. However, if you combine the complexities of having multiple iodine species present with the uncertainty of having hobbyists use very complex test kits that may readily yield incorrect or difficult to interpret results, the stage is set for people driving their total iodine to levels far from what they actually intended. I do not know what levels of iodide or iodate become apparently problematic to real aquaria, but the risk of overdosing in this fashion is not insignificant."
Iodine Part 1
http://advancedaquarist.com/issues/mar2003/chem.htm
Iodine Part 2
http://www.advancedaquarist.com/issues/april2003/chem.htm_________________Keepin' marines happy for 25 years

Last edited by FloridaBoy on 2010.05.17(Mon)5:43; edited 1 time in total

Thanks for your reply, going on what you say and what the web sites say I think I will avoid it, I have had my 60 gallon tank for 3 years now and have never had a problem with any type of Alge, so don't want to add anything that might encourage it, I was told that it could be good for my Tubastraeas as I have 2 orange cup ones, one with about 20 heads and one with about 110 heads and also a Black cup with around 50 heads and as you can imagine I don't want to put them at risk as they are my pride and joy, I even bought a Nitrate Filter so I can feed them every day.
Thanks again for your reply
Glen.
ps I will try and post a photo so you can let me know what you think

Very good Glen, yes please post a few photos and provide some details on the feeding process so others can benefit, thank you. Ultimately, we all have to do what we think is best for our animals; and it's not always an easy task when there is so much anecdotal evidence and contradictory information floating around.

Reminds me of the "garlic wars." I have seen aquarists swear by garlic in marine aquaria; I say more power to them, but I also tend to take these comments with a grain of salt. I am not immune to it myself; for example I have personally seen head and lateral line erosion (HLLE) brought on by what appeared to be a reaction to the use of activated carbon. But I have to remind myself there are many variables within these observations, and at the end of the day it's just an observation, not measured or scientific data._________________Keepin' marines happy for 25 years

Glen: use a photo hosting website such as photobucket. resize the photo so it is no more than 600x800 (theres tools right in photobucket for you to do this), copy and paste the link photobucket creates for your photo into the message box here, with the IMG button clicked before and after you paste the link.

Should look like:

[img]www.picturelinkgoeshere.com[/img]_________________Let the current take you where you may not always want to go.